Process for removal of benzoic acid from an oxidizer purge stream

Abstract

A process is disclosed that relates to the removal of impurities, specifically benzoic acid, from a mother liquor produced in the synthesis of carboxylic acid, typically terephthalic acid.

1. A process comprising:
 (a) subjecting a benzoic acid bearing stream comprising water and benzoic acid to evaporation in an evaporator zone to form a solvent rich vapor and a wash filtrate residue; and 
 (b) subjecting said solvent rich vapor to distillation in a separation zone to form a solvent rich stream and a benzoic acid rich stream; 
  wherein said benzoic acid rich stream comprises at least 15% by weight benzoic acid. 
 
     
     
       2. The process according to  claim 1  wherein said benzoic acid rich stream comprises benzoic acid in an amount greater than 30% by weight. 
     
     
       3. The process according to  claim 1  wherein said benzoic acid bearing stream is produced in an aromatic oxidation process. 
     
     
       4. The process according to  claim 1  wherein said benzoic acid bearing stream is a vapor stream produced in the oxidation of an aromatic compound. 
     
     
       5. The process according to  claim 1  wherein said evaporator zone is operated between about 1 to about 10 atmospheres. 
     
     
       6. A process comprising:
 (a) subjecting a benzoic acid bearing stream comprising water and benzoic acid to evaporation in an evaporator zone to form a solvent rich vapor and a wash filtrate residue; and 
 (b) subjecting said solvent rich vapor to distillation in a separation zone to form a solvent rich stream and a benzoic acid rich stream; 
  wherein said benzoic acid rich stream comprises at least 15% by weight benzoic acid; and 
 (c) recycling at least a portion of the solvent rich stream back to an oxidation reactor in an aromatic oxidation process. 
 
     
     
       7. The process according to  claim 6  wherein said benzoic acid rich stream comprises benzoic acid in an amount greater than 30% by weight. 
     
     
       8. The process according to  claim 6  wherein said benzoic acid bearing stream is produced in an aromatic oxidation process. 
     
     
       9. The process according to  claim 6  wherein said benzoic acid bearing stream is a vapor stream produced in the oxidation of an aromatic compound. 
     
     
       10. The process according to  claim 6  wherein at least 50 wt % of said benzoic acid rich stream is recycled to an oxidation reactor in an aromatic oxidation process. 
     
     
       11. The process according to  claim 6  wherein said evaporator zone is operated between about 1 to about 10 atmospheres. 
     
     
       12. A process comprising:
 (a) subjecting a benzoic acid bearing stream comprising water and benzoic acid to evaporation in an evaporator zone to form a solvent rich vapor and a wash filtrate residue; wherein said benzoic acid bearing stream is produced in an aromatic oxidation process; 
 (b) subjecting said solvent rich vapor to distillation in a separation zone to form a solvent rich stream and a benzoic acid rich stream; 
  wherein said benzoic acid rich stream comprises from about 5 wt % to about 35 wt % benzoic acid; and 
 (c) recycling at least 50 wt % of the solvent rich stream to an oxidation reactor in an aromatic oxidation process. 
 
     
     
       13. The process according to  claim 12  wherein said benzoic acid bearing stream is a vapor stream produced in the oxidation of an aromatic compound. 
     
     
       14. The process according to  claim 12  wherein at least 75 wt % of said benzoic acid rich stream is recycled to an oxidation reactor in an aromatic oxidation process. 
     
     
       15. The process according to  claim 12  wherein said evaporator zone is operated between about 1 to about 10 atmospheres. 
     
     
       16. The process according to  claim 12  wherein all of the solvent rich stream is recycled to an oxidation reactor process.